Cell balancing is a fundamental technique that improves battery life by maximizing the capacity of a battery pack with multiple cells in series. By ensuring that all cells have a similar state of charge, cell balancing ensures that all of the battery's energy is available for use. In this article, we will explore how cell balancing improves battery life and examine active and passive cell balancing methods.

Cell balance and its importance

Cell balancing is a key function in a battery management system, such as those found in lithium-ion battery packs, electric vehicles, and energy storage applications.

The individual cells in a battery pack often have different capacities and states of charge SOC](__NCP_TOKEN_0__). Without charge redistribution, discharge must stop when the cell with the lowest capacity becomes empty, even if the rest are not yet empty, thus limiting the power delivery capacity of the pack.

If cell balancing is not done, there is a weak point in the cell with the least capacity. In this sense, the BMS has this function as its main one, along with others of vital importance such as thermal control, charging and other factors that maximize the useful life of the battery pack.

How does cell balancing improve battery life?

👉 Cell balancing improves battery life by ensuring that all cells in a battery pack have a similar state of charge.

On the one hand, cell balancing ensures that all battery cells are discharged in a balanced manner, allowing you to make the most of the total capacity of the battery pack.

Additionally, cell balancing prevents some cells from overcharging or discharging more than others, which can irreparably damage them and reduce battery life.

The risk of thermal runaway caused by overcharging or overdischarging is also reduced, helping to maintain battery temperatures within safe ranges.

Finally, it is important because it minimizes degrading processes by preventing some cells from overcharging or discharging more than others, which prolongs the life of the battery by maintaining its capacity and efficiency over time.

There are 2 types of cellular balance: active balance and passive balance.

Active cellular balance: advantages and limitationsActive cell balancing involves transferring energy from one cell to another within the battery pack. This is achieved through converter circuits that channel energy from cells with a higher voltage or load to those with a lower voltage or load. Some advantages of active cell balance include:

• Improved capacity utilization.

• Increased energy efficiency by avoiding the dissipation of energy in the form of heat.

• Extension of the useful life of the cells.

• Fast swinging.

Although active cellular balance has several benefits, it also has some limitations, such as:

• Power loss during charge transfer (approximately 10% to 20%).

• Limitation to transfer charge only from a higher cell to a lower one.

• Greater complexity in control algorithms and higher production cost due to the need for additional power electronic interfaces.

Passive cell balancing: advantages and limitations

Passive cell balancing involves the burning of excess energy from the most charged cells through resistive elements until the charge in all cells is equalized.

Some advantages of passive cell balancing are:

• Does not require balancing a battery pack.

• Avoid wasting energy from a cell that does not have it.

• Allows all cells to have the same state of charge (SoC).

• Offers an economical approach to balancing cells.

Passive cell rolling also has some limitations, such as:

• Poor thermal management.

• It is not completely balanced throughout the SoC, which implies the waste of excess energy.

• Low power transmission efficiency due to thermal and switching losses.

• Does not improve the runtime of a battery powered system.

Conclusion

Balancing a battery's cells focuses on matching the state of charge (SoC) of each individual cell, rather than matching its total capacity. If the battery pack is properly balanced from the factory, the Battery Management System (BMS) only needs to monitor the balance current. This is especially beneficial as battery packs can be built that are already balanced, eliminating the need for a BMS to perform a full balance.The goal of any balancing method is to allow the battery pack to operate at peak performance and extend its useful capacity. For those who want to minimize costs and correct any long-term imbalances in the cells' self-discharge current, passive balancing is the best option. With passive balance, a cell cannot waste energy it does not have. Only when the power bank is fully charged does a cell have enough energy to balance itself, thus avoiding any unnecessary wastage of energy

The technology that NCPOWER has patented that improves the performance and efficiency of batteries thanks to the cell balancing system, the NCPOWER System is a third alternative to traditional balancing systems.

The NCPOWER System prevents the drawbacks of the 2 previous balancing systems and also improves the positive parts of said systems.

What makes NCPOWER different? What exactly does the NCPOWER System consist of? Here we show you the NCPOWER System.